| 摘要 |
PURPOSE:To obtain iron carbide fine particles with enhanced magnetic properties and corrosionproofness by specifying the weight change thereof under the combustion conditions. CONSTITUTION:The objective iron carbide fine particles consists mainly of iron carbide with the weight gain at the equilibrium state after the attainment of the maximum weight through its combustion being <=22%. Said particles can be obtained by the following process: oxyferric hydroxide or ferric hydroxide particles are brought into contact with a carbon-free reducible gas, or no contact therewith, followed by contact with a carbonizable gas or its mixture with a carbon-free reducible gas at 250-395 deg.C and furthermore, contact with a carbonizable gas at temperatures higher than the above temperature by 5-20 deg.C for 0.5-5hr. The iron carbide fine particles thus obtained is outstanding in magnetic properties and stability with small reduction rate of the saturation magnetization level even in high-temperature and oxidized state. |
